Apparatus and method for transmitting/receiving multiuser packet in a mobile communication system

ABSTRACT

An apparatus and method is provided for generating one packet with transmission data and transmitting the packet from an access network transceiver system (ANTS) to a plurality of access terminals (ATs) in a mobile communication system including the ATs and the ANTS which are capable of performing packet data communication with ATs located in coverage thereof. The method includes the steps of generating a medium access control (MAC) header including information on a receiving AT&#39;s address, a length and format for transmission data, generating a MAC payload by consecutively connecting data units to be transmitted to the receiving AT, and generating a MAC trailer. The ANTS pads ‘0’ bits to the MAC header if a predetermined MAC size is greater than a sum of lengths of the MAC header, the MAC payload and the MAC trailer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(a) of KoreanPatent Application No. 10-2005-0001893 entitled “Apparatus and Methodfor Transmitting/Receiving Multiuser Packet in a Mobile CommunicationSystem” filed in the Korean Intellectual Property Office on Jan. 7,2005, and Korean Patent Application No. 10-2005-0087443 entitled“Apparatus and Method for Transmitting/Receiving Multiuser Packet in aMobile Communication System” filed in the Korean Intellectual PropertyOffice on Sep. 20, 2005, the entire disclosure of both of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an apparatus and method fortransmitting/receiving data in a mobile communication system. Inparticular, the present invention relates to an apparatus and method fortransmitting/receiving packet data in a mobile communication system.

2. Description of the Related Art

Mobile communication systems have been developed to provide voiceservices, guaranteeing the mobility of a user. With the rapid progressin communication technology, mobile communication systems have evolvedinto systems that are capable of providing data service as well.Recently, research has been conducted on high-speed data transmission ina Code Division Multiple Access (CDMA) mobile communication system. A 1×Evolution Data Only (1×EVDO) system is a typical mobile communicationsystem having a channel structure for the high-speed data transmission.The 1×EVDO system was proposed in the 3^(rd) Generation PartnershipProject 2 (3GPP2) to complement data communication of the IS-2000system.

In the 1×EVDO system, data communication can be divided into forwarddata communication and reverse data communication. The term “forwarddata communication” refers to data communication from an access network(or base station) to an access terminal (or mobile station), while theterm “reverse data communication” refers to data communication from anaccess terminal to an access network. A description will now be made ofexemplary structures of forward channels in the 1×EVDO system. Theforward channels are classified as a pilot channel, a forward MediumAccess Control (MAC) channel, a forward traffic channel, and a forwardcontrol channel, all of which are transmitted to an access terminalafter being subjected to Time Division Multiplexing (TDM). A set of theTDM transmission signals is called a “burst.”

Among these channels, the forward traffic channel transmits a user datapacket, and the forward control channel transmits a control message anda user data packet. In addition, the forward MAC channel is used forreverse rate control, transmission of power control information, andassignment of forward data channel.

A description will now be made of reverse channels used in the 1×EVDOsystem. Unlike the forward channels, the reverse channels used in the1×EVDO system have different identification codes unique to accessterminals. Therefore, in the following description, the “reversechannels” refer to channels transmitted to an access network withdifferent identification codes unique to the access terminals. Thereverse channels comprise a pilot channel, a reverse traffic channel, anaccess channel, a Data Rate Control (DRC) channel, and a Reverse RateIndicator (RRI) channel.

Functions of the reverse channels will now be described in greaterdetail. The reverse traffic channel, like the forward traffic channel,transmits a user data packet in the reverse direction. The DRC channelis used to indicate a forward data rate that the access terminal cansupport, and the RRI channel is used to indicate a rate of a datachannel transmitted in the reverse direction. The access channel is usedwhen the access terminal transmits a message or traffic to the accessnetwork before the traffic channel is connected. With reference to FIG.1, a description will now be made of a configuration of the 1×EVDOsystem, a rate control operation, and its associated channels.

FIG. 1 is a conceptual diagram illustrating a 1×EVDO mobilecommunication system.

Referring to FIG. 1, reference numeral 100 denotes access terminals(ATs), reference numeral 110 denotes access network transceiver systems(ANTSs), and reference numeral 120 denotes access network controllers(ANCs). A brief description of the system configuration will now bemade. A first ANTS 110 a communicates with a plurality of ATs 100 a and100 b, and a second ANTS 110 b communicates with an AT 100 c. The firstANTS 110 a is connected to a first ANC 120 a, and the second ANTS 10 bis connected to a second ANC 120 b. Each of the ANCs 120 a and 120 b canbe connected to two or more ANTSs. In FIG. 1, one ANC is connected toonly one ANTS, as an example. The ANCs 120 a and 120 b are connected toa packet data service node (PDSN) 130 that provides a packet dataservice, and the PDSN 130 is connected to an Internet network 140.

In the exemplary mobile communication system of FIG. 1, each of theANTSs 110 a and 110 b transmits packet data to only the AT having thehighest packet data rate among the ATs located in its coverage. Adetailed description thereof will now be made. In the followingdescription, an AT will be denoted by reference numeral 100, and an ANTSwill be denoted by reference numeral 110.

For rate control of a forward channel, an AT 100 measures receptionstrength of a pilot channel transmitted by an ANTS 110, and determines aforward data rate desired by the AT 100 according to a fixed valuepredetermined based on the measured pilot reception strength.Thereafter, the AT 100 transmits DRC information corresponding to thedetermined forward data rate to the ANTS 110 over a DRC channel. Thenthe ANTS 110 receives DRC information from all of the ATs intending tocommunicate therewith, located in its coverage. Based on the DRCinformation, the ANTS 110 can transmit packet data to only a particularAT having a good channel quality condition at a data rate reported bythe AT. The DRC information refers to a value determined from a possibleforward data rate calculated by the AT by measuring its channelcondition. Although a mapping relationship between the forward channelcondition and the DRC information is subject to change according toimplementation, typically the mapping relationship is fixed in themanufacturing process of the AT.

The mapping relationship between the DRC value reported by an AT and itsassociated data rate and transmission format is shown in Table 1 below,by way of example. TABLE 1 Data Rate Number of TX Transmission DRC(kbps) (slots) Format 0x0 0 16 (1024, 16, 1024) 0x1 38.4 16 (1024, 16,1024) 0x2 76.8 8 (1024, 8, 512) 0x3 153.6 4 (1024, 4, 256) 0x4 307.2 2(1024, 2, 128) 0x5 307.2 4 (2048, 4, 128) 0x6 614.4 1 (1024, 1, 64) 0x7614.4 2 (2048, 2, 64) 0x8 921.6 2 (3072, 2, 64) 0x9 1228.8 1 (2048, 1,64) 0xa 1228.8 2 (4096, 2, 64) 0xb 1843.2 1 (3072, 1, 64) 0xc 2457.6 1(4096, 1, 64) 0xd 1536 2 (5120, 2, 64) 0xe 3072 1 (5120, 1, 64)

It can be noted from Table 1 that the transmission format is expressedin the form of (A, B, C). The transmission format will be describedherein below with reference to a first field of Table 1, as an example.In the transmission format (A, B, C), C=1024 indicates 1024-bitinformation, B=16 indicates that the information is transmitted for 16slots, and A=1024 indicates that a 1024-chip preamble is transmitted.Therefore, an ANTS transmits data to an AT with the transmission formatcorresponding to a DRC value reported by the AT. After reporting the DRCvalue, the AT attempts to receive a forward data channel only with thetransmission format corresponding to the reported DRC value. Thisagreement is made because no other channel exists to indicate a datarate for a data channel transmitted in the forward direction. That is,when the ANTS transmits data using a transmission format other than thetransmission format reported by the AT, there is no way to indicate thetransmission format, so that the AT cannot receive the data. Therefore,the ANTS transmits data only with the transmission format correspondingto (compatible with) the DRC reported by the AT. For example, for an ATthat transmitted DRC=0x01 over a DRC channel, the ANTS transmits datausing a transmission format (1024, 16, 1024) corresponding to the DRCvalue, and the AT attempts to receive the data with only thetransmission format of the corresponding DRC value.

The packet data that the ANTS transmits to one AT according to receivedDRC information in accordance with the method of Table 1 is called a“single user packet.” The ANTS transmits data using the single userpacket for the general data service. Compared with the general dataservice, such a data service as voice-over-Internet protocol (VoIP)requires a lower transmission bandwidth of about 9.6 kbps, in which,data of about 192 bits is transmitted every 20 ms. However, transmittingthe short data through the single user packet having a minimum size of1024 bits causes unnecessary bandwidth waste. In order to prevent theresource waste in the wireless access section, a scheme for transmittingdata for several users through one physical placket has been introduced,and this packet format is called a “multiuser packet.” The multiuserpacket will now be described with reference to Table 2 below, by way ofexample. TABLE 2 Rate List of Associated DRC (kbps) Multi-UserTransmission Formats 0x0 0 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256) 0x1 38.4 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256) 0x2 76.8 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256) 0x3 153.6 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256) 0x4 307.2 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256) 0x5 307.2 (128, 4, 256), (256, 4, 256), (512, 4, 256),(1024, 4, 256), (2048, 4, 128) 0x6 614.4 (128, 4, 256), (256, 4, 256),(512, 4, 256), (1024, 4, 256) 0x7 614.4 (128, 4, 256), (256, 4, 256),(512, 4, 256), (1024, 4, 256), (2048, 4, 128) 0x8 921.6 (128, 4, 256),(256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2,64) 0x9 1228.8 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4,256), (2048, 4, 128) 0xa 1228.8 (128, 4, 256), (256, 4, 256), (512, 4,256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096, 2, 64) 0xb1843.2 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256),(2048, 4, 128), (3072, 2, 64) 0xc 2457.6 (128, 4, 256), (256, 4, 256),(512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096, 2,64) 0xd 1536 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4,256), (2048, 4, 128), (3072, 2, 64), (4096, 2, 64), (5120, 2, 64) 0xe3072 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048,4, 128), (3072, 2, 64), (4096, 2, 64), (5120, 2, 64)

Table 2 illustrates an exemplary format of the multiuser packet for eachDRC in the 1×EVDO system. In Table 2, each DRC index includes itsassociated data rate and a format of a packet to be transmitted tomultiple users. A description thereof will be made with reference to afifth field of Table 2, as an example. That is, a format of a multiuserpacket transmitted to multiple ATs that transmitted DRC=5 is given as(128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4,128). This multiuser packet includes packet data for several users, andis transmitted together with the addresses of the ATs that will receivethe packet data. An AT, upon receiving the multiuser packet, determineswhether its own address is included in the received multiuser packet,and if its own address is included therein, processes a user packetcorresponding thereto.

Although transmission of the multiuser packet is being discussed in3GPP2 that has established the CDMA 1×EVDO standard, there is nodiscussion on how to transmit an address of the multiuser packet.Accordingly, there is a need for an apparatus and method that is capableof detecting the case where one packet is commonly transmitted tomultiple users rather than a single user, and reporting the detectionresult to each of the users.

SUMMARY OF THE INVENTION

An object of the present invention is to substantially solve the aboveand other problems, and provide an apparatus and method for designatingusers during transmission/reception of a multiuser packet in a mobilecommunication system.

Another object of the present invention is to provide an apparatus andmethod for detecting transmission of a packet including mixed data formultiple users and reporting the detection result in a mobilecommunication system.

Another object of the present invention is to provide an apparatus andmethod that is capable of receiving and processing a packet includingmixed data for multiple users in a mobile communication system.

According to one aspect of the present invention, a method is providedfor generating one packet with transmission data and transmitting thepacket from an access network transceiver system (ANTS) to a pluralityof access terminals (ATs) in a mobile communication system including theATs and the ANTS which are capable of performing packet datacommunication with ATs located in coverage thereof. The method comprisesthe steps of generating a medium access control (MAC) header includinginformation on a receiving AT's address, and a length and format fortransmission data, generating a MAC payload by consecutively connectingdata units to be transmitted to the receiving AT, and generating a MACtrailer, wherein ‘0’ bits are padded to the MAC header if apredetermined MAC size is greater than a sum of lengths of the MACheader, the MAC payload and the MAC trailer.

According to another aspect of the present invention, a method isprovided for receiving a multiuser packet in a mobile communicationsystem including access terminals (ATs) and an access networktransceiver system (ANTS) that performs packet communication with ATslocated in coverage thereof, and generates the multiuser packet withtransmission data to be transmitted to two or more ATs. The methodcomprises the steps of receiving the multiuser packet from the ANTS,wherein the multiuser packet comprises a medium access control (MAC)header including information on each AT's address and a length andformat for the transmission data, a MAC payload generated byconsecutively connecting data units to be transmitted to each AT, and aMAC trailer, wherein ‘0’ bits are padded to the MAC header if apredetermined MAC size is greater than a sum of lengths of the MACheader, the MAC payload and the MAC trailer. The method furthercomprises the steps of determining whether address information of the ATis included in the MAC header of the received multiuser packet, andextracting data indicated by the MAC header from the MAC payload of themultiuser packet if the address information of the AT is included in theMAC header.

According to another aspect of the present invention, an apparatus forgenerating one packet with transmission data and transmitting the packetfrom an access network transceiver system (ANTS) to a plurality ofaccess terminals (ATs) in a mobile communication system including theATs and the ANTS which are capable of performing packet datacommunication with ATs located in coverage thereof. The apparatuscomprises data queues for storing data to be transmitted to each of theATs, a controller for performing a control operation of generating amedium access control (MAC) header including information on a receivingAT's address, a length and format for transmission data, generating aMAC trailer, and generating a MAC payload by consecutively connectingdata units to be transmitted to the receiving AT, and performing acontrol operation of padding ‘0’ bits to the MAC header if apredetermined MAC size is greater than a sum of lengths of the MACheader, the MAC payload and the MAC trailer. The apparatus furthercomprises a data generation and transmission/reception unit for, underthe control of the controller, combining the data stored in the dataqueues and information output from the controller, and transmitting thecombined result to the ATs.

According to yet another aspect of the present invention, an apparatusis provided for receiving a multiuser packet in a mobile communicationsystem including access terminals (ATs) and an access networktransceiver system (ANTS) that performs packet communication with ATslocated in coverage thereof, and generates the multiuser packet withtransmission data to be transmitted to two or more ATs. The apparatuscomprises a reception data processor for receiving the multiuser packetfrom the ANTS, wherein the multiuser packet comprises a medium accesscontrol (MAC) header including information on each AT's address and alength and format for the transmission data, a MAC payload generated byconsecutively connecting data units to be transmitted to each AT, and aMAC trailer, wherein ‘0’ bits are padded to the MAC header if apredetermined MAC size is greater than a sum of lengths of the MACheader, the MAC payload and the MAC trailer, and for demodulating anddecoding the received multiuser packet. The apparatus further comprisesa controller for determining whether address information of the AT isincluded in the MAC header of the received multiuser packet, andextracting data indicated by the MAC header from the MAC payload of themultiuser packet if the address information of the AT is included in theMAC header.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a conceptual diagram illustrating an exemplary 1×EVDO mobilecommunication system;

FIG. 2A is a diagram illustrating an efficient format of a multiuserpacket according to a first embodiment of the present invention FIGS. 2Band 2C are diagrams illustrating different formats of a PacketInfo fieldin a MAC header of a multiuser packet according to the first embodimentof the present invention;

FIG. 3A is a diagram illustrating a modified format of a multiuserpacket according to the first embodiment of the present invention;

FIG. 3B is a diagram illustrating a format of PacketInfo field in amodified MAC header for a multiuser packet according to the firstembodiment of the present invention;

FIG. 4 is a flowchart illustrating a process of generating a multiuserpacket in an ANTS according to the first embodiment of the presentinvention;

FIG. 5 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the first embodiment ofthe present invention;

FIG. 6A is a diagram illustrating an exemplary efficient format of amultiuser packet according to a second embodiment of the presentinvention;

FIG. 6B illustrates an efficient format of a PacketInfo field in a MACheader for a multiuser packet according to the second embodiment of thepresent invention;

FIG. 7 is a flowchart illustrating a process of generating a multiuserpacket in an ANTS according to the second embodiment of the presentinvention;

FIG. 8 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the second embodiment ofthe present invention;

FIG. 9A is a diagram illustrating an exemplary efficient format of amultiuser packet according to a third embodiment of the presentinvention;

FIG. 9B is a diagram illustrating a format of a PacketInfo field in aMAC header for a multiuser packet according to the third embodiment ofthe present invention;

FIG. 10 is a flowchart illustrating a process of generating a multiuserpacket in an ANTS according to the third embodiment of the presentinvention;

FIG. 11 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the third embodiment ofthe present invention; and

FIG. 12 is a block diagram illustrating structures of an ANTS and an ATaccording to an exemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention will now be described ingreater detail with reference to the accompanying drawings. In thefollowing description, a detailed description of known functions andconfigurations incorporated herein will be omitted for clarity andconciseness.

In the following description, exemplary embodiments of the presentinvention disclose an efficient format of a multiuser packet, the formatcomprising information on an address of an access terminal (AT)scheduled to receive the multiuser packet and information on a lengthand configuration of the packet. The following description of thepresent invention will provide three exemplary embodiments, but is notlimited thereto.

First Embodiment

FIG. 2A is a diagram illustrating an efficient format of a multiuserpacket according to a first embodiment of the present invention. Withreference to FIG. 2A, a detailed description will now be made of anefficient format of a multiuser packet according to a first embodimentof the present invention.

A multi-user packet shown in FIG. 2A is roughly divided into threeparts, comprising:

(1) Medium Access Control (MAC) header 210,

(2) MAC payload 220, and

(3) MAC trailer 230.

The MAC header 210, a part including information on addresses, lengthsand formats of several user packets included in a MAC packet, comprisesa minimum of one PacketInfo field or a maximum of 8 PacketInfo fields.Although the number of the PacketInfo fields is extendable, thepreferred maximum number of the PacketInfo fields becomes 8 when a sizeof a packet provided in the 1×EVDO system is taken into consideration.Therefore, the minimum number and maximum number of the PacketInfofields are subject to change for other systems. The PacketInfo field inthe MAC header 210 can have a format as shown in FIG. 2B or a format asshown in FIG. 2C.

FIGS. 2B and 2C are diagrams illustrating different formats of aPacketInfo field in a MAC header of a multiuser packet according to thefirst embodiment of the present invention. Referring to FIG. 2B, aPacketInfo field 211 with a 2-octet length comprises a 1-bit Formatfield 211 a indicating format information of the MAC packet, a 7-bitMACIndex field 211 b indicating a receiving AT of the MAC packet, and an8-bit Length field 211 c indicating a length of the MAC packet. That is,the 8 most significant bits (MSB) of the 2-octect PacketInfo fieldcannot have a value of ‘00000000’. Referring to FIG. 2C, a NULLPacketInfo field 212 with a 1-octet length has all zero values‘00000000’ over the 1 octet. Because the 8 MSB bits of the former field211 cannot have a value of ‘00000000’, a receiving AT can distinguish aformat of the former field 211 from a format of the latter field 212.The NULL PacketInfo field 212 is used to distinguish the MAC header 210from the MAC payload 220 in the MAC packet. The NULL PacketInfo field212 is added to an end of the MAC header 210 when the number of userpackets included in the MAC packet is less than 8 and the user packetscannot fully fill the MAC payload 220.

The MAC payload 220 comprises actual user packets included in the MACpacket. The MAC payload 220 is generated by consecutively connectingpackets for multiple users such that a user security layer packet(hereinafter referred to as a “user packet” for simplicity)corresponding to information on an i^(th) PacketInfo field of the MACheader 210 is located in an i^(th) point of the MAC payload 220.

The MAC trailer 230 comprises information indicating a format of the MACpacket, and has a value of ‘00’ for a format of a multiuser packet.

FIG. 3A is a diagram illustrating a modified format of a multiuserpacket according to the first embodiment of the present invention. Withreference to FIG. 3A, a detailed description will now be made of amodified format of a multiuser packet according to the first embodimentof the present invention.

The overall format of FIG. 3A is substantially equal to the format ofFIG. 2A. Similarly, the multiuser packet shown in FIG. 3A is roughlydivided into three parts comprising a MAC header 310, a MAC payload 320and a MAC trailer 330.

Compared with the MAC header 210 having the PacketInfo field 211generated by consecutively connecting the Format field 211 a indicatingformat information of a user packet, the MACIndex field 211 b indicatinga user identifier (ID), and the Length field 211 c indicating a lengthof the user packet, the MAC header 310 as shown in FIG. 3B comprises aPacketInfo field 311 generated by connecting a Format field 311 a and aMACIndex field 311 b, without including the Length field 211 c.Similarly, a NULL PacketInfo field in the format of FIG. 3A is used fordistinguishing the MAC header 310 from the MAC payload 320 in the MACpacket. The NULL PacketInfo field is added to an end of the MAC header310 when the number of user packets included in the MAC packet is lessthan 8 and the user packets cannot fully fill the MAC payload 320.Therefore, the PacketInfo field 311 of FIG. 3B has a one-octet length,and includes the 1-bit Format field 311 a and the 7-bit MACIndex field311 b.

FIG. 4 is a flowchart illustrating a process of generating a multiuserpacket (MUP) in an access network transceiver system (ANTS) according tothe first embodiment of the present invention. With reference to FIG. 4,a detailed description will now be made of a process of generating amultiuser packet in an ANTS according to the first embodiment of thepresent invention. It should be noted that the process of FIG. 4 can beapplied to either the basic format or the modified format. In thefollowing description, FIGS. 2A through 2C will be referred to as FIG.2, and FIGS. 3A and 3B will be referred to as FIG. 3, for convenience.

In step 400, an ANTS selects a packet #i for a particular user, to betransmitted using a multiuser packet. In step 402, the ANTS generates aPacketInfo field and a Length field shown in FIG. 2 or 3 using formatinformation, a receiving AT's ID, and a length for the packet #i. Afterthe packet generation, the ANTS determines in step 404 whether thepacket #i having the PacketInfo field and the Length field can be addedto a remaining space of a MAC packet. If it is determined in step 404that the packet #i can be added to the remaining space, the ANTSproceeds to step 406. Otherwise, if the packet #i cannot be added, theANTS proceeds to step 410 where it determines whether there are any moreuser packets to add. If there are any packets to add, the ANTS returnsto step 400. Otherwise, the ANTS proceeds to step 412.

In step 406, the ANTS adds the PacketInfo field and the Length field ofthe packet #i to an end of a MAC header of the MAC packet, and adds thepacket #i to an end of a MAC payload. After completion of adding the newpacket #i in step 406, the ANTS determines in step 408 whether the MACpacket includes a maximum possible number of, for example, 8 userpackets. If it is determined that the number of user packets included inthe MAC packet has not reached the maximum possible number, the ANTSproceeds to step 410 where it determines whether there are any morepackets to add.

However, if it is determined in step 408 that the MAC packet includes 8user packets, i.e., a maximum possible number of user packets, the ANTSstops adding new packets and proceeds to step 412 where it determineswhether there is any empty spaces in the MAC packet. If it is determinedthat there is an empty space in the MAC packet, the ANTS determines instep 414 whether the corresponding MAC packet includes a maximumpossible number of, for example, 8 user packets. If it is determinedthat the MAC packet includes 8 user packets, i.e., a maximum possiblenumber of user packets, the ANTS adds enough ‘0’-padding to fill up aMAC payload in step 416, and then ends the process. However, if it isdetermined in step 414 that the MAC packet includes less than 8 userpackets, the ANTS adds a NULL PacketInfo field of ‘00000000’ to an endof the MAC header to distinguish between the MAC header and the MACpayload, and adds enough ‘0’-padding to fill up the empty space of theMAC payload in step 418, completing the generation of the multiuserpacket.

FIG. 5 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the first embodiment ofthe present invention. With reference to FIG. 5, a detailed descriptionwill now be made of a process of analyzing a format of a receivedmultiuser packet by an AT according to the first embodiment of thepresent invention.

In step 500, an AT receiving a multiuser packet sets a value of aparameter sum_packet_length indicating a sum of lengths of all userpackets included in the received multiuser packet, to ‘0’. In step 502,the AT reads a value of an i^(th) PacketInfo field from the multiuserpacket shown in FIG. 2 or 3, and determines whether the read valueequals ‘00000000’. If the read value equals ‘00000000’, the AT candetermine that the number of user packets included in the multiuserpacket is i-1. In this case, the AT decreases a value of i by one instep 506, and sets the new value of i as the number of user packetsincluded in the multiuser packet in step 516. Thereafter, the AT canextract i packets in the multiuser packet based on information analyzedusing i PacketInfo fields and Length fields in step 518.

If it is determined in step 502 that the read value does not equal‘00000000’, the AT checks format information, a receiving AT's ID, and alength for the i^(th) user packet corresponding to the read i^(th)PacketInfo field and Length field in step 504. Thereafter, in step 508,the AT adds the length of the i^(th) user packet to the parametersum_packet_length. In step 510, the AT estimates a size of the MACpayload for the case where i user packets are included in the multiuserpacket. The estimation can be performed by subtracting lengths of iPacketInfo fields and Length fields and a length (2 bits) of a MACtrailer from the total length of the MAC packet, reported from aphysical layer. In step 512, the AT determines whether the determinedlength of the MAC payload is equal in value to the parametersum_packet_length. If the two values are equal to each other, the AT candetermine in step 516 that the number of user packets included in theMAC packet is i. In step 518, the AT can extract i packets in themultiuser packet based on information analyzed using the i PacketInfofields and Length fields. However, if it is determined in step 512 thatthe length of the MAC payload is different in value from the parametersum_packet_length, the AT determines in step 514 whether a value of ihas reached 8 which is the maximum possible number of user packetsincluded in the multiuser packet. If the value of i is equal to 8, theAT can determine the number of user packets included in the MAC packetas 8 in step 516, and extract 8 user packets in the multiuser packetbased on information analyzed using the 8 PacketInfo fields and Lengthfields in step 518.

However, if it is determined in step 514 that the value of i is notequal to 8, the AT returns to step 502 and performs its succeeding stepsagain to read information on the next user packet.

Second Embodiment

FIG. 6A is a diagram illustrating an exemplary efficient format of amultiuser packet according to a second embodiment of the presentinvention. With reference to FIG. 6A, a detailed description will now bemade of an efficient format of a multiuser packet according to thesecond embodiment of the present invention.

Substantially as described above, a multi-user packet shown in FIG. 6Acan be roughly divided into three parts, comprising:

(1) MAC header 610,

(2) MAC payload 620, and

(3) MAC trailer 630.

The MAC header 610, a part including information on addresses, lengthsand formats of several user packets included in a MAC packet, comprisesa minimum of one Length field or a maximum of 8 Length fields, andcomprises a minimum of one PacketInfo field or a maximum of 8 PacketInfofields. Similarly, the number of the PacketInfo fields is extendable.However, the preferred maximum number of the PacketInfo fields becomes 8when a size of a packet provided in the 1×EVDO system is taken intoconsideration. Therefore, the minimum number and maximum number of thePacketInfo fields are subject to change for other systems. Referring toFIG. 6B, a PacketInfo field 621 in the MAC header 610 comprises a 1-bitFormat field 621 a indicating a format of a user packet and a 7-bitMACIndex field 621 b indicating an ID of a receiving AT for the userpacket. FIG. 6B illustrates an efficient format of a PacketInfo fieldconstituting a MAC header for a multiuser packet according to the secondembodiment of the present invention. The number of the Length fields isgreater by one than the number of the PacketInfo fields when the numberof user packets included in the MAC packet is less than 8 and a sum oflengths of the user packets is less than a size of the MAC payload 620.For example, in this case, the MAC header 610 may comprise 4 Lengthfields and 3 PacketInfo fields. The last Length field included in theMAC header 610 has a value of ‘00000000’ to indicate a boundary betweenthe Length fields and the PacketInfo fields.

The MAC payload 620 comprises actual user packets included in the MACpacket. The MAC payload 620 is generated by consecutively connectingpackets for multiple users such that a user security layer packet(hereinafter referred to as a “user packet” for simplicity)corresponding to information on an i^(th) PacketInfo field of the MACheader 610 is located in an i^(th) point of the MAC payload 620.Finally, the MAC trailer 630 comprises information indicating a formatof the MAC packet, and has a value of ‘00’ for a format of a multiuserpacket.

A description will now be made of a process of transmitting a multiuserpacket in an ANTS and a process of receiving the multiuser packet in anAT according to the second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a process of generating a multiuserpacket in an ANTS according to the second embodiment of the presentinvention. With reference to FIG. 7, a detailed description will now bemade of a process of generating a multiuser packet in an ANTS accordingto the second embodiment of the present invention. In the followingdescription, FIGS. 6A and 6B will be referred to as FIG. 6, forconvenience.

In step 700, an ANTS selects a packet #i for a particular user, to betransmitted using a multiuser packet. In step 702, the ANTS generates aPacketInfo field shown in FIG. 6 using format information and areceiving AT's ID for the packet #i. Thereafter, the ANTS determines instep 704 whether the packet #i and a Length field and a PacketInfo fieldfor packet #i can be added to a remaining space of a MAC packet. If itis determined in step 704 that they can be added to the remaining space,the ANTS proceeds to step 706 where it adds the Length field and thePacketInfo field for the packet #i to the last Length field and the lastPacketInfo field of the MAC header, respectively, to satisfy the formatshown in FIG. 6, and adds the packet #i to an end of a MAC payload.However, if it is determined in step 704 that the packet #i cannot beadded to the remaining space, the ANTS proceeds to step 710 where itdetermines whether there are any more user packets to add.

After completion of adding the new packet #i in step 706, the ANTSdetermines in step 708 whether the MAC packet includes a maximumpossible number of, for example, 8 user packets. If it is determinedthat the number of user packets included in the MAC packet has notreached the maximum possible number, the ANTS proceeds to step 710 whereit determines whether there are any more user packets to add. However,if it is determined in step 708 that the MAC packet includes 8 userpackets, i.e., a maximum possible number of user packets, the ANTS stopsadding new packets and proceeds to step 712 where it determines whetherthere are any empty spaces in the MAC packet. Also, if it is determinedin step 710 that there are no more user packets to add, the ANTS stopsadding new packets and proceeds to step 712, where it determines whetherthere are any empty spaces in the MAC packet.

However, if it is determined in step 710 that there are more userpackets to add, the ANTS returns to step 700 and performs its succeedingsteps.

If it is determined in step 712 that there is an empty space in the MACpacket, the ANTS determines in step 714 whether the corresponding MACpacket includes a maximum possible number of, for example, 8 userpackets. If it is determined that the MAC packet includes 8 userpackets, i.e., a maximum possible number of user packets, the ANTS addsenough ‘0’-padding to fill up the MAC payload in step 716, and then endsthe process. However, if it is determined in step 714 that the MACpacket includes less than 8 user packets, the ANTS adds a Length fieldof ‘00000000’ to the last Length field in the MAC header to distinguishbetween Length fields and PacketInfo fields in the MAC header, and addsenough ‘0’-padding to fill up the empty space of the MAC payload in step718, completing generation of the multiuser packet.

FIG. 8 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the second embodiment ofthe present invention. With reference to FIG. 8, a detailed descriptionwill now be made of a process of analyzing a format of a receivedmultiuser packet by an AT according to the second embodiment of thepresent invention.

In step 800, an AT receiving a multiuser packet sets a value of aparameter sum_packet_length indicating a sum of lengths of all userpackets included in the received multiuser packet, to ‘0’. In step 802,the AT reads a value of an i^(th) Length field from the multiuser packetshown in FIG. 6, and determines whether the read value equals‘00000000’. If the read value equals ‘00000000’, the AT can determinethat the number of user packets included in the multiuser packet is i-1.In this case, the AT decreases a value of i by one in step 806, and setsthe new value of i as the number of user packets included in themultiuser packet in step 816. Thereafter, the AT can extract i packetsin the multiuser packet based on information analyzed using i Lengthfields and PacketInfo fields in step 818.

However, if it is determined in step 802 that the read value does notequal ‘00000000’, the AT checks format information and a receiving AT'sID for the i^(th) user packet corresponding to a read i^(th) PacketInfofield for the read i^(th) Length field in step 804. Thereafter, in step808, the AT adds the length of the i^(th) user packet to the parametersum_packet_length. In step 810, the AT estimates a size of the MACpayload for the case where i user packets are included in the multiuserpacket. The estimation can be performed by subtracting lengths of iLength fields and PacketInfo fields and a length (2 bits) of a MACtrailer from the total length of the MAC packet, reported from aphysical layer. In step 812, the AT determines whether the determinedlength of the MAC payload is equal in value to the parametersum_packet_length. If the two values are equal to each other, the AT candetermine in step 816 that the number of user packets included in theMAC packet is i. In this case, the AT can extract i packets in themultiuser packet based on information analyzed using the i Length fieldsand PacketInfo fields, in step 818.

However, if it is determined in step 812 that the length of the MACpayload is different in value from the parameter sum_packet length, theAT determines in step 814 whether a value of i has reached 8 which isthe maximum possible number of user packets included in the multiuserpacket. If the value of i is equal to 8, the AT can determine the numberof user packets included in the MAC packet as 8 in step 816, and extract8 user packets in the multiuser packet based on information analyzedusing the 8 Length fields and PacketInfo fields in step 818.

However, if it is determined in step 814 that the value of i is notequal to 8, the AT returns to step 802 and performs its succeeding stepsagain to read information on the next user packet.

Third Embodiment

FIG. 9A is a diagram illustrating an exemplary efficient format of amultiuser packet according to a third embodiment of the presentinvention. With reference to FIG. 9A, a detailed description will now bemade of an efficient format of a multiuser packet according to the thirdembodiment of the present invention.

Substantially as described above, a multi-user packet shown in FIG. 9Acan be roughly divided into three parts, comprising:

(1) MAC header 910,

(2) MAC payload 920, and

(3) MAC trailer 930.

Each of n MAC headers 910 is a part including information on addresses,lengths and formats of several user packets included in a MAC packet.Each of the n MAC headers 910 can comprise a minimum of one Length fieldor a maximum of 8 Length fields, and a minimum of one PacketInfo fieldor a maximum of 8 PacketInfo fields. Similarly, the possible number ofthe PacketInfo fields included in the MAC packet is extendable. However,the preferred maximum number of the PacketInfo fields becomes 8 when asize of a packet provided in the 1×EVDO system is taken intoconsideration. Therefore, the minimum number and maximum number of thePacketInfo fields are subject to change for other systems.

Referring to FIG. 9B, a PacketInfo field 911 in the MAC header 910comprises a 1-bit Format field 911 a indicating a format of a userpacket and a 7-bit MACIndex field 911 b indicating an ID of a receivingAT for the user packet. Each of the n MAC payloads 920 comprises actualuser packets included in the MAC packet. The MAC payload 920 transmits auser security layer packet (hereinafter referred to as a “user packet”for simplicity) corresponding to information on a PacketInfo field ofits preceding MAC header. The MAC trailer 930 comprises informationindicating a format of the MAC packet, and has a value of ‘00’ for aformat of a multiuser packet.

FIG. 10 is a flowchart illustrating a process of generating a multiuserpacket in an ANTS according to the third embodiment of the presentinvention. With reference to FIG. 10, a detailed description will now bemade of a process of generating a multiuser packet in an ANTS accordingto the third embodiment of the present invention. In the followingdescription, FIGS. 9A and 9B will be referred to as FIG. 9, forconvenience.

In step 1000, an ANTS selects a packet #i for a particular user, to betransmitted using a multiuser packet. In step 1002, the ANTS generates aPacketInfo field shown in FIG. 9 using format information and areceiving AT's ID for the packet #i. Thereafter, the ANTS determines instep 1004 whether the packet #i and a Length field and a PacketInfofield for packet #i can be added to a remaining space of a MAC packet.If it is determined in step 1004 that they can be added to the remainingspace, the ANTS proceeds to step 1006 where it adds the packet #i andthe Length field and the PacketInfo field for the packet #i to the lastadded user packet and the last Length field and the last PacketInfofield for the user packet, respectively, to satisfy the format shown inFIG. 9.

However, if it is determined in step 1004 that the packet #i cannot beadded to the remaining space, the ANTS proceeds to step 1010 where itdetermines whether there are any more user packets to add. If there aremore user packets to add, the ANTS returns to step 1000 and repeatedlyperforms its succeeding steps. However, if there are no more userpackets to add, the ANTS proceeds to step 1012.

After completion of adding the new packet #i in step 1006, the ANTSdetermines in step 1008 whether the MAC packet includes a maximumpossible number of, for example, 8 user packets. If it is determinedthat the number of user packets included in the MAC packet has notreached the maximum possible number, the ANTS proceeds to step 1010where it determines whether there are any more user packets to add.

However, if it is determined in step 1008 that the MAC packet includes 8user packets, i.e., a maximum possible number of user packets, the ANTSstops adding new packets and proceeds to step 1012 where it determineswhether there are any empty spaces in the MAC packet. If it isdetermined that there is an empty space in the MAC packet, the ANTS addsenough ‘0’-padding to fill up the MAC payload in step 1014, and thenends the process. However, if there is no empty space in the MAC packet,the ANTS ends the process without ‘0’-padding.

FIG. 11 is a flowchart illustrating a process of analyzing a format of areceived multiuser packet by an AT according to the third embodiment ofthe present invention. With reference to FIG. 11, a detailed descriptionwill now be made of a process of analyzing a format of a receivedmultiuser packet by an AT according to the third embodiment of thepresent invention.

In step 1100, an AT receiving a multiuser packet sets a value of aparameter sum_packet_length indicating a sum of lengths of all userpackets included in the received multiuser packet, to ‘0’. In step 1102,the AT reads a value of an i^(th) Length field from the multiuser packetshown in FIG. 9, and determines whether the read value equals‘00000000’. In the third embodiment of the present invention, because avalue of the Length field cannot become ‘00000000’, the AT can determinethat the read value of ‘00000000’ is a start of a padding part.Therefore, the AT can determine that the number of user packets includedin the multiuser packet is i-1. In this case, the AT decreases a valueof i by one in step 1106, and sets the new value of i as the number ofuser packets included in the multiuser packet in step 1116. Thereafter,the AT can extract i packets in the multiuser packet based oninformation analyzed using i Length fields and PacketInfo fields in step1118.

However, if it is determined in step 1102 that the read value does notequal ‘00000000’, the AT checks format information and a receiving AT'sID for the i^(th) user packet corresponding to a read i^(th) PacketInfofield for the read i^(th) Length field in step 1104. Thereafter, in step1108, the AT adds the length of the i^(th) user packet to the parametersum_packet_length. In step 1110, the AT estimates a size of the MACpayload for the case where i user packets are included in the multiuserpacket. The estimation can be performed by subtracting lengths of iLength fields and PacketInfo fields and a length (2 bits) of a MACtrailer from the total length of the MAC packet, reported from aphysical layer. In step 1112, the AT determines whether the determinedlength of the MAC payload is equal in value to the parameter sum_packetlength. If the two values are equal to each other, the AT performs step1116 and its succeeding step in the manner described above.

However, if it is determined in step 1112 that the length of the MACpayload is different in value from the parameter sum_packet_length, theAT determines in step 1114 whether a value of i has reached 8 which isthe maximum possible number of user packets included in the multiuserpacket. If the value of i is equal to 8, the AT proceeds to step 1116.Otherwise, if the value of i is not equal to 8, the AT returns to step1102 and performs its succeeding steps again to read information on thenext user packet.

A description will now be made of structures of an ANTS and an ATaccording to an exemplary embodiment of the present invention.

FIG. 12 is a block diagram illustrating structures of an ANTS and an ATaccording to an exemplary embodiment of the present invention. Withreference to FIG. 12, a detailed description will now be made ofstructures of an ANTS and an AT according to an embodiment of thepresent invention.

A structure and operation of an ANTS 1210 will first be described hereinbelow. The ANTS 1210 corresponds to the ANTS 110 shown in FIG. 1, but isnot limited thereto. An ANTS controller 1211 controls a process ofgenerating a multiuser packet with a format shown in FIGS. 2, 3, 6 and9. A data queue 1213 stores user data received from an upper node 1212separately for individual users. For example, the upper node 1212corresponds to the ANC 120 of FIG. 1. The ANTS controller 1211 detectsthe data stored in the data queue 1213, and performs a control operationof generating and transmitting a multiuser packet according tocharacteristics of the data before transmission.

That is, the ANTS controller 1211 controls transmission of the datastored in the data queue 1213. When transmitting a single user packet,the ANTS controller 1211 outputs data stored in only one data queue to adata generation and transmission/reception unit 1214. However, whentransmitting a multiuser packet, the ANTS controller 1211 reads datafrom a plurality of data queues 1213 and outputs the read data to thedata generation and transmission/reception unit 1214 in order togenerate a multiuser packet with a format shown in FIGS. 2, 3, 6 and 9using user data stored in the plurality of data queues 1213 beforetransmission. Then the data generation and transmission/reception unit1214 generates a transmission burst under the control of the ANTScontroller 1211, and transmits the transmission burst through acorresponding wireless band.

Next, a structure and operation of an AT 1200 will be described. The AT1200 corresponds to the AT 100 of FIG. 1, but is not limited thereto. Inthe AT 1200, a radio frequency (RF) unit 1201 frequency-down-converts anRF signal received from an antenna into a baseband signal, and outputsthe baseband signal to a demodulator 1202. The demodulator 1202demodulates the baseband signal modulated during its transmission, andoutputs the demodulated data to a decoder 1203. The decoder 1203 decodesthe demodulated data encoded during its transmission, and outputs thedecoded data to an AT controller 1204 together with a CRC error checkresult. The RF unit 1201, the demodulator 1202 and the decoder 1203comprise a reception data processor.

The AT controller 1204 controls the operations of FIGS. 5, 8 and 11,using the data received at the reception data processor. That is, for amultiuser packet, the AT controller 1204 performs a control operation ofprocessing its own multiuser packet transmitted thereto. Description ofother control operations performed by the AT controller 1204 will beomitted for clarity and conciseness.

In addition, the AT controller 1204 generates a control signal to betransmitted in the reverse direction, and provides the generated controlsignal to an encoder 1206. The encoder 1206 encodes the user data andthe control signal, and outputs the encoded data to a modulator 1207.The modulator 1207 performs modulation with a modulation method selectedaccording to the characteristics of the data, and outputs the modulateddata to the RF unit 1201. The RF unit 1201 frequency-up-converts thedata received from the modulator 1207 into an RF signal, andreverse-transmits the RF signal to the ANTS 1210 via an antenna. Theencoder 1206, the modulator 1207 and the RF unit 1201 comprise atransmission data processor.

The RF unit 1201 can be included in both the reception data processorand the transmission data processor. The RF unit 1201 may furtherinclude a reception unit for the reception data processor and atransmission unit for the transmission data processor.

As can be understood from the foregoing description, the novel apparatusand method of embodiments of the present invention can efficientlytransmit information included in a packet to each of multiple usersother than a single user.

While exemplary embodiments of the invention have been shown anddescribed with reference to a certain exemplary implementations thereof,it will be understood by those skilled in the art that various changesin form and details may be made therein without departing from thespirit and scope of the invention as defined by the appended claims.

1. A method for generating one packet with transmission data andtransmitting the packet from an access network transceiver system (ANTS)to a plurality of access terminals (ATs) in a mobile communicationsystem including the ATs and the ANTS which are capable of performingpacket data communication with ATs located in coverage thereof, themethod comprising the steps of: generating a medium access control (MAC)header comprising information on a receiving AT's address, a length anda format for transmission data; generating a MAC payload byconsecutively connecting data units to be transmitted to the receivingAT; and generating a MAC trailer, wherein ‘0’ bits are padded to the MACheader if a predetermined MAC size is greater than a sum of lengths ofthe MAC header, the MAC payload and the MAC trailer.
 2. The method ofclaim 1, wherein a number n of the MAC payloads is 1≦n≦8.
 3. The methodof claim 1, wherein the ‘0’ bits are padded in octet units.
 4. Themethod of claim 3, wherein the ‘0’ bits are padded to the MAC payload ifthe MAC size is not satisfied after the ‘0’ bits are padded to the MACheader.
 5. The method of claim 4, wherein the ‘0’ bits are padded to theMAC payload after a maximum possible number of the ‘0’ bits are paddedto the MAC header.
 6. An apparatus for generating one packet withtransmission data and transmitting the packet from an access networktransceiver system (ANTS) to a plurality of access terminals (ATs) in amobile communication system including the ATs and the ANTS which arecapable of performing packet data communication with ATs located incoverage thereof, the apparatus comprising: data queues for storing datato be transmitted to each of the ATs; a controller for performing acontrol operation of generating a medium access control (MAC) headercomprising information on a receiving AT's address, a length and aformat for transmission data, generating a MAC trailer, and generating aMAC payload by consecutively connecting data units to be transmitted tothe receiving AT, and performing a control operation of padding ‘0’ bitsto the MAC header if a predetermined MAC size is greater than a sum oflengths of the MAC header, the MAC payload and the MAC trailer; and adata generation and transmission/reception unit for, under the controlof the controller, combining the data stored in the data queues andinformation output from the controller, and transmitting the combinedresult to the ATs.
 7. The apparatus of claim 6, wherein a number n ofthe MAC payloads is 1≦n≦8.
 8. The apparatus of claim 6, wherein thecontroller pads the ‘0’ bits in octet units.
 9. The apparatus of claim8, wherein the controller pads the ‘0’ bits to the MAC payload if theMAC size is not satisfied after padding the ‘0’ bits to the MAC header.10. The apparatus of claim 9, wherein the controller pads the ‘0’ bitsto the MAC payload after padding a maximum possible number of the ‘0’bits to the MAC header.
 11. A method for receiving a multiuser packet ina mobile communication system including access terminals (ATs) and anaccess network transceiver system (ANTS) that performs packetcommunication with ATs located in coverage thereof, and generates themultiuser packet with transmission data to be transmitted to two or moreATs, the method comprising the steps of: receiving the multiuser packetfrom the ANTS, wherein the multiuser packet comprises a medium accesscontrol (MAC) header comprising information on each AT's address and alength and a format for the transmission data, a MAC payload generatedby consecutively connecting data units to be transmitted to each AT, anda MAC trailer, wherein ‘0’ bits are padded to the MAC header if apredetermined MAC size is greater than a sum of lengths of the MACheader, the MAC payload and the MAC trailer; determining whether addressinformation of the AT is included in the MAC header of the receivedmultiuser packet; and extracting data indicated by the MAC header fromthe MAC payload of the multiuser packet if the address information ofthe AT is included in the MAC header.
 12. An apparatus for receiving amultiuser packet in a mobile communication system including accessterminals (ATs) and an access network transceiver system (ANTS) thatperforms packet communication with ATs located in coverage thereof, andgenerates the multiuser packet with transmission data to be transmittedto two or more ATs, the apparatus comprising: a reception data processorfor receiving the multiuser packet from the ANTS, wherein the multiuserpacket comprises a medium access control (MAC) header comprisinginformation on each AT's address and a length and a format for thetransmission data, a MAC payload generated by consecutively connectingdata units to be transmitted to each AT, and a MAC trailer, wherein ‘0’bits are padded to the MAC header if a predetermined MAC size is greaterthan a sum of lengths of the MAC header, the MAC payload and the MACtrailer, and demodulating and decoding the received multiuser packet;and a controller for determining whether address information of the ATis included in the MAC header of the received multiuser packet, andextracting data indicated by the MAC header from the MAC payload of themultiuser packet if the address information of the AT is included in theMAC header.